Recent developments in the field of action recognition technology have enabled detection of particular actions that a person may perform, on the basis of pictures or videos taken by an imaging device. A part of such development efforts has been directed to techniques for determining whether a person has picked up an object. Such actions may be detected by analyzing data of pictures containing images of a person.
For example, one proposed technique extracts some appropriate areas from a given picture to detect entry or exit of a human hand, examines the three-dimensional position of a hand in each of the extracted areas, and determines whether an object has been taken out of its original place, on the basis of variations in the top-edge width of an area containing the hand. Another proposed technique captures frame images of, for example, a product shelf and evaluates frame-to-frame differences to detect whether a product is picked up from the shelf. See, for example, the documents listed below.
Japanese Laid-open Patent Publication No. 2001-128814
Japanese Laid-open Patent Publication No. 2011-253344
The above-described conventional techniques may, however, exhibit some inaccuracy in particular cases. For example, the technique based on frame-to-frame differences may mistakenly detect that a product is picked up in the case where the product has actually fallen off the shelf as a result of an accidental contact with a customer's body.